The original concept for Portal 2 featured a different main character, but the concept behind how the game would start was largely the same. Here, the player is waking up in a gorgeous environment designed to look like paradise--but it quickly falls apart in
An alternate intro to the game
The co-op story was also different. Originally set after the events of Portal 2, GLaDOS originally sent the robotic pair on quests to find human "artifacts" in order to become more human. One such artifact was this comic, obviously inspired by
Co-op had players retrieving human artifacts
Portal 2's original ending was quite the opposite of the astronomical finale gamers were ultimately presented. One concept had players needed to use a voice command to take back control from the game's final villain. Poking fun at Chell's apparent muteness, the game would fade to black as Chell uttered one word that would close the game--"yes."
Chell would've no longer been mute